Apparatus for treating dry flocculent powders



Aug. 2'7, 19409 R. w. SKOOG ET AL APPARATUS FOR TREATING DRY FLOCCULENTPOWDERS Filed April 29, 1938 M @4 9 jzTTbkNEi Patented Aug. 27, 1940 IUNITED ,STATES APPARATUS FOR TREATING nmz FLOCGULENT POWDERS Robert W.Skoog and Thomas J. Bradford,

Burger, Tex., assignors to United Carbon Company, Inc., Charleston, W.Va., a corporation of Delaware Application April 29, 1938, Serial No.205,140

-. q 3 Claims.

The present invention relates to an apparatus for treating dryflocculent powders for the purpose of forming substantially dustlessagglomerates therefrom. One field to which the present invention isparticularly applicable is the manufacture of the so-called "dustlesscarbon black in accordance with the disclosures of the copendingapplication of Hilding Hanson and Robert W. Skoog, Ser. No. 205,139,filed April 29, 1938.

It is a principal object of the present invention to provide anapparatus for treating dry flocculent powders which will impart to awetted mass of such powders a definite size and shape without destroyingthe identity of the individual particles of the powder.

It is a further object of the present invention to provide an apparatusfor treating dry flocculent powders to form substantially dustlessagglomerates thereof,the apparatus being particularly adapted for use incontinuous processes for the formation of small substantially sphericalagglomerates of the flocculent material, part of which is wetted by aliquid wetting agent and part of which is utilized in its dry state.

Another object of the present invention is to provide an apparatus fortreating finely divided fiocculent powders to form composite wet-dryagglomerates of self-sustaining forms capable of ready and uniformdispersion in a selected dispersion medium, the agglomerates occupying adecreased space and being more readily shipped, stored and handled thanthe unagglomerated flocculent powder, the novel apparatus hereindisclosed permitting simplification of controls and lowered fuelrequirements to dry the agglomerates, thus possessing many features ofcommercial advantage over the apparatus heretoforc known in the art.

A further object of the present invention is to provide an improvedapparatus for treating flocculent powders to form graular particlesgenerally spherical in shape, the particles being nonadherent andpossessing suflicient density to resist ready displacement in the airand of such shapes and strengths as to resist crushing in normalhandling and shipping, while possessing a readily frangible structurewhich permits ready breaking of the particles to make available thediscrete individual particles of the original powder for dispersion in adispersion medium.

Other objects of this invention will appear in the following descriptionand appendedclaims, reference being had to the accompanying drawing 5forming a part of this specification, wherein like reference charactersdesignate corresponding parts in the several views.

Fig. l is a diagrammatic view of one form of apparatus embodying thepresent invention.

Fig. 2 is a side elevation with parts broken away 6 showing the interiorconstruction of a preferred form of device embodying the presentinvention.

Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig. 2looking in the direction of the arrows.

Fig. 4 is a cross sectional view taken substantially on the line 4-4 ofFig. 2 looking in the direction of the arrows.

Fig. 5 is an elevation with parts broken away of a modified form ofapparatus embodying the 5 present invention.

Before explaining in detail the present invention it is to be understoodthat the invention is not limited in its application to the details ofconstruction and arrangement of parts illustrated in the accompanyingdrawing, since the invention is capable of other embodiments and ofbeing practiced or carried out in various ways. Also it is to beunderstood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation, and it is not intendedto limit the invention claimed herein beyond the requirements of theprior art.

The present invention is intended for use in processes wherein dryflocculent powders are formed into substantially dustless' agglomerates.Inthe preferred embodiment of the invention herein disclosed by way ofexample but not of limitation, the apparatus is particularly designedfor use in a so-called wet process or with a socalled wet and dryprocess. In either of the processes the agglomerates are initiallyformed from a plastic mass of the dry flocculent powder which has beenwetted with a suitable wetting agent. Such a wetting agent must benon-redo active with the dry powder and must not effect any appreciablechange in the chemical or physical condition of the individual particlesof the treated powder. In the instance where carbon black is the drypowder to be treated, water is a desirable wetting agent.

As shown in the diagrammatic view of Fig. 1 the apparatus consistsessentially of a cylindrical drum it which is mounted on a plurality ofdriving rollers II which support the casing l0 and impart a rotarymovement thereto. Since many methods are known for imparting suchrotarymotion to a drum it is to be understood that any suitable type ofrotating mechanism may be employed within the scope of the presentinvention.

The dry flocculent powder is continuously charged into a hopper |2 fromany suitable source of such powder and feeds through a conduit I3 to theinterior of the drum H]. In the case where carbon black is the powder tobe treated, it maybe fed to the hopper or directly to the drum by aconveyor leading from the burner house. The wetting agent is supplied tothe interior of the drum I0 through the conduit l4 and its flow iscontrolled by the valve I5. When a dry flocculent powder, such forexample as carbon black, is charged into the hopper I2 and fed to theinterior of the cylindrical chamber Ill, water is fed through theconduit 4. The flow of the carbon black and of the water is so regulatedthat substantially equal amounts by weight of carbon black and water arefed into the cylinder I0. As the wetted carbon black traverses thelength of the cylinder I0 it is formed into a plurality of separateparticles which are substantially spherical in Shape and these particlesare discharged through the discharge duct l6 from which they may beconveyed by the conveyor H .to the desired type of drying apparatuswherein the moisture content of the particles is reduced.

If desired, the particles discharged from the conduit l6 may be fed intoa hopper of another device identical to that which is described, whereinthe wetted black particles will be charged into the hopper |2 and a dryflocculent powder will be introduced to the interior of the drum l0 fromthe other hopper. The admixed wetted carbon black particles and the dryflocculent powder will then be acted upon by the apparatus and will bedischarged as a plurality of small spherical agglomerates through thedischarge duct |B from which such wet and dry agglomerates may becarried to any suitable drying device for removing the remainingmoisture from the particles. In such an operation it is desirable thatthe mixing members he so arranged that a different direction of rotarymotion is imparted to the particles in the separate members.

The interior of the drum ll] is shown in Figs. 2, 3 and 4. As thereshown, a central shaft 20 extends lengthwise of the drum and is providedwith a plurality of extending pins or arms 2| rigidly secured thereto.The arms 2| are arranged longitudinally of the shaft with their centerslying on a substantially helical line extending from end to end aroundthe shaft. Successive arms are arranged at an angle of approximately toeach other. By this arrangement, the arms 2| cause the material workedupon to advance progressively through the drum from the inlet to thedischarge opening. During this travel through the drum, the material isformed into spherical shaped agglomerates due to the action of the arms2| and the action of the plurality of pins or arms 22 which are securedto the interior of the drum l0 and extend inwardly thereof on radiallines in staggered circumferential courses adjacent the paths of thearms 2| and lengthwise of the drum. This arrangement is clearly shown inFigs. 3 and 4. The shaft 20 may be a stationary shaft or the shaft maybe power driven. In either instance the drum Ill revolves about thecenter line of the shaft as an axis. The shaft 20 may be power driven inthe same direction of rotation as the drum ID, in which instance it ispreferable that the speeds of rotation of the shaft and of the drumshould be different. It is, however, preferable that the shaft 20revolve in the opposite direction of the direction of rotation of thedrum I0 and that the shaft 20 revolve at a. different speed than thespeed of revolution of the drum I0.

In a preferred embodiment of the invention the drum It! was constructedas a cylindrical shell of approximately 30 inches in diameter and 10feet in length. The pins 22 which were secured to the shell each wereapproximately 10 inches long and of approximately inch in diameter. Thecourses of the pins were spaced approximately 2% inches apart andextended circumferentially of the shell. The pins or arms 2| on theshaft 20 in this embodiment of the invention were each approximately 14inches long and inch in diameter. The pins were located spirally of theshaft 20, in staggered relation to each other, and were spacedapproximately 2 inches between centers. As shown in Fig. 2 the pins 2|extend radially outward of the shaft 20 and are placed at an angle ofapproximately 90 to the succeeding or preceding pin or arm 2|. Thisconstruction operating on wetted carbon black produced a mass ofsubstantially spherical pellets which were progressively advancedthrough the drum and discharged through the discharge .openingcommunicating with the conduit I6.

A modified form of apparatus is shown in Fig. 5. As there shown themixing apparatus comprises a cylindrical drum 30 which is rotatablymounted on a plurality of supporting and driving roller members 32. Abafile member 33 is secured to the inside of the drum 30 and separatesthe drum into a wet mixing portion 34 and a dry mixing portion 35. Thewet mixing portion 34 is formed substantially as shown in Fig. 2 with aplurality of pins 36 secured to the shell 30 and a plurality of pins 37secured to a hollow shaft member 38. In this instance the shaft member38 is preferably stationary and has an open conduit portion 39 whichextends through the baflle 33 and discharges into the portion 35.

The operation of this apparatus may be substantially as follows:

A conveyor 40 discharges a dry flocculent powder into the interior ofthe mixing portion 34 of the drum 30. A suitable wetting agent isintroduced into the interior of the drum 3!] through a conduit 42. Theflow of wetting agent is regulated by the valve 43. The rotation of thedrum 3!] causes the wetting agent and the dry agglomerated powder to bethoroughly mixed and causes the mass to assume the form of small wetspherical agglomerates during the course of travel of the masstransversely of the mixing portion 34 of the drum 30. The wetagglomerated spherical particles are discharged through an opening 44 inthe battle 33 and drop into the dry agglomerating section 35. A dryflocculent powder as for example carbon black is fed through theinterior of the hollow shaft 38 and is discharged through the dischargeopening 39 where it falls into the agglomerating section 35. The wetparticles and the dry flocculent powder are thoroughly admixed and aresubjected to a continuous agitation while being subjected to drying.This action is that of a rotary tumbling device. The rotation of thedrum 30 causes the dry powder to adhere to the wet particles and toabsorb some of the moisture from the wet pellets so that the pelletsgrow in size without materially increasing the moisture content of thelarger agglomerates. The combined wet and dry said courses, a bafflesecured in said drum at the I agglomerated particles arev thendischarged through a discharge duct 45 after having traversed the entirelength of the cylindrical shell 30.

' ing a specific weight of approximately 24 lbs. per Y The particles arethen conveyed to a suitable drier where the moisture content is furtherreduced.

As disclosed inthe co-pending application of Robert W. Skoog and HildingHanson, Ser. No. 205,139, a typical example of a product which wasmanufactured in the device' herein shown using the wet and dry method ofagglomerating carbon black as therein disclosed, consisted of smallspherical particles of dustless carbon black havthe product on standardtesting screens it, was

found that approximately 97.69% was retained on a 100 mesh screen,approximately 1.47% was retained 'on a 200 mesh screen and approximately0.38% was retained on a 300 mesh screen. The balance passed through thescreen and was recovered from the pan.

The-dried product possesses a novel structure due to the method offorming the particle by the combined wet and dry agglomeratlng actionhere disclosed. The nucleus of the particles formed by the wetagglomerating action is in general more densely compacted than is theshell formed by the agglomerated dry powders. The essentially amorphousnature of the shell permits ready dryingof the interior of theagglomerated particles and is also readily broken up to permitdispersion of the individual particles into a selected dispersionmedium. The formation of the wet-dry agglomerates as herein disclosed ismore rapid than either a whblly wet or a wholly dry agglomeratlng end ofsaid wet agglomerating section, a dry agglomerating sectioncommunicating with said wet agglomerating section and communicating withthe discharge opening in said hollow shaft, said dry agglomeratingsection being adapted to admix dry flocculent powders with the wetagglomerates from said first named section while maintaining saidagglomerates and dry powder in intimate rolling contact with each other,

2. An apparatus particularly adapted to form substantially dustlessagglomerates of dry floccu lent powders, said apparatus comprising arotatable drum having a wet agglomerating section and a dryagglomerating section, said wet aggiomerating section having a series ofinwardly extending radial pins arranged in circumferential courses,means for feeding said powders into said drum, means for feeding awetting agent into said drum, a shaft extending longitudinally of saiddrum and having radial arms extending between adjacent courses of pinsin said drum and adapted to form said powders into wetted substantiallyspherical agglomerates, said dry agglomerating section comprising atumbling section having an inlet communicating directly with said wetagglomerating section for receiving said wetted agglomerates therefrom,and an inlet for dry flocculent powders, said dry agglomerating sectionbeing adapted to admix said wetted agglomerates with said dry powdersand to form substantially dustless agglomerates therefrom.

'3. An apparatus for forming substantially spherical shaped agglomeratesof flocculent powders comprising a cylindrical drum containing a wetagglomerating section adapted to form wetted nuclei of the agglomeratedpowders and comprising a series of radial pins secured to a forwardsection of said drum and extending inwardly thereof in circumferentialcourses, means for feeding said powders into said drum, means forfeeding a wetting agent into saidv drum, a shaft having radiallyextending arms arranged spirally of the shaft and extending between saidcourses of pins on the drum, an annular bame secured in said drum at theend of said wet agglomerating section and having a central openingtherei a dry agglomerating section adapted to admix dry flocculentpowder with the wet glomerated nuclei and communicating with said wetagglomeratlng section through said central opening in said annularbaffle, and an inlet in said dry agglomerating section for introducingdry 'flocculent powder into said section.

ROBERT W. SKOOG. THOMAS J. BRADFORD.

